Commit 93ada1b3 authored by Yoav Cohen's avatar Yoav Cohen Committed by Jens Axboe
Browse files

ublk: add UBLK_CMD_TRY_STOP_DEV command 



Add a best-effort stop command, UBLK_CMD_TRY_STOP_DEV, which only stops a
ublk device when it has no active openers.

Unlike UBLK_CMD_STOP_DEV, this command does not disrupt existing users.
New opens are blocked only after disk_openers has reached zero; if the
device is busy, the command returns -EBUSY and leaves it running.

The ub->block_open flag is used only to close a race with an in-progress
open and does not otherwise change open behavior.

Advertise support via the UBLK_F_SAFE_STOP_DEV feature flag.

Signed-off-by: default avatarYoav Cohen <yoav@nvidia.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9e386f49

drivers/block/ublk_drv.c

+42 −2
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ 
#define UBLK_CMD_DEL_DEV_ASYNC	_IOC_NR(UBLK_U_CMD_DEL_DEV_ASYNC)

#define UBLK_CMD_UPDATE_SIZE	_IOC_NR(UBLK_U_CMD_UPDATE_SIZE)

#define UBLK_CMD_QUIESCE_DEV	_IOC_NR(UBLK_U_CMD_QUIESCE_DEV)

#define UBLK_CMD_TRY_STOP_DEV	_IOC_NR(UBLK_U_CMD_TRY_STOP_DEV)



#define UBLK_IO_REGISTER_IO_BUF		_IOC_NR(UBLK_U_IO_REGISTER_IO_BUF)

#define UBLK_IO_UNREGISTER_IO_BUF	_IOC_NR(UBLK_U_IO_UNREGISTER_IO_BUF)
@@ -76,7 +77,8 @@ 
		| UBLK_F_QUIESCE \

		| UBLK_F_PER_IO_DAEMON \

		| UBLK_F_BUF_REG_OFF_DAEMON \

		| (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) ? UBLK_F_INTEGRITY : 0))

		| (IS_ENABLED(CONFIG_BLK_DEV_INTEGRITY) ? UBLK_F_INTEGRITY : 0) \

		| UBLK_F_SAFE_STOP_DEV)



#define UBLK_F_ALL_RECOVERY_FLAGS (UBLK_F_USER_RECOVERY \

		| UBLK_F_USER_RECOVERY_REISSUE \
@@ -243,6 +245,8 @@ struct ublk_device { 
	struct delayed_work	exit_work;

	struct work_struct	partition_scan_work;



	bool			block_open; /* protected by open_mutex */



	struct ublk_queue       *queues[];

};
@@ -984,6 +988,9 @@ static int ublk_open(struct gendisk *disk, blk_mode_t mode) 
			return -EPERM;

	}



	if (ub->block_open)

		return -ENXIO;



	return 0;

}
@@ -3343,7 +3350,8 @@ static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_cmd *header) 
	ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE |

		UBLK_F_URING_CMD_COMP_IN_TASK |

		UBLK_F_PER_IO_DAEMON |

		UBLK_F_BUF_REG_OFF_DAEMON;

		UBLK_F_BUF_REG_OFF_DAEMON |

		UBLK_F_SAFE_STOP_DEV;



	/* GET_DATA isn't needed any more with USER_COPY or ZERO COPY */

	if (ub->dev_info.flags & (UBLK_F_USER_COPY | UBLK_F_SUPPORT_ZERO_COPY |
@@ -3464,6 +3472,34 @@ static void ublk_ctrl_stop_dev(struct ublk_device *ub) 
	ublk_stop_dev(ub);

}



static int ublk_ctrl_try_stop_dev(struct ublk_device *ub)

{

	struct gendisk *disk;

	int ret = 0;



	disk = ublk_get_disk(ub);

	if (!disk)

		return -ENODEV;



	mutex_lock(&disk->open_mutex);

	if (disk_openers(disk) > 0) {

		ret = -EBUSY;

		goto unlock;

	}

	ub->block_open = true;

	/* release open_mutex as del_gendisk() will reacquire it */

	mutex_unlock(&disk->open_mutex);



	ublk_ctrl_stop_dev(ub);

	goto out;



unlock:

	mutex_unlock(&disk->open_mutex);

out:

	ublk_put_disk(disk);

	return ret;

}



static int ublk_ctrl_get_dev_info(struct ublk_device *ub,

		const struct ublksrv_ctrl_cmd *header)

{
@@ -3859,6 +3895,7 @@ static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub, 
	case UBLK_CMD_END_USER_RECOVERY:

	case UBLK_CMD_UPDATE_SIZE:

	case UBLK_CMD_QUIESCE_DEV:

	case UBLK_CMD_TRY_STOP_DEV:

		mask = MAY_READ | MAY_WRITE;

		break;

	default:
@@ -3972,6 +4009,9 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, 
	case UBLK_CMD_QUIESCE_DEV:

		ret = ublk_ctrl_quiesce_dev(ub, header);

		break;

	case UBLK_CMD_TRY_STOP_DEV:

		ret = ublk_ctrl_try_stop_dev(ub);

		break;

	default:

		ret = -EOPNOTSUPP;

		break;

include/uapi/linux/ublk_cmd.h

+8 −1
Original line number Diff line number Diff line
@@ -55,7 +55,8 @@ 
	_IOWR('u', 0x15, struct ublksrv_ctrl_cmd)

#define UBLK_U_CMD_QUIESCE_DEV		\

	_IOWR('u', 0x16, struct ublksrv_ctrl_cmd)



#define UBLK_U_CMD_TRY_STOP_DEV		\

	_IOWR('u', 0x17, struct ublksrv_ctrl_cmd)

/*

 * 64bits are enough now, and it should be easy to extend in case of

 * running out of feature flags
@@ -321,6 +322,12 @@ 
 */

#define UBLK_F_INTEGRITY (1ULL << 16)



/*

 * The device supports the UBLK_CMD_TRY_STOP_DEV command, which

 * allows stopping the device only if there are no openers.

 */

#define UBLK_F_SAFE_STOP_DEV	(1ULL << 17)



/* device state */

#define UBLK_S_DEV_DEAD	0

#define UBLK_S_DEV_LIVE	1